This is just a rough outline of ideas that I'm perfectly willing to adjust.
Basically, my idea is that the running theme for the game is that Factol Ombidias of the Mind's Eye is investigating the Illuminated Eye cult and it's possible ties to the religion of Aoskar. He doesn't suspect they're trying to resurrect the dead god at this point but is merely curious what they're up to (he's actually thinking that Aola wants to seize the Factolship for himself).
I think the players will find the Illuminated Eye seeking some relic of Aoskar in the past or something similar in an Indiana Jones style quest for the object.
Eventually, Factol Ombidias is going to be assassinated in the game by Dexter's minions. This is going to result in one of the Mind's Eye that the players have befriended going on trial. It turns out that it's actually her twin brother that carried out the deed (Saross and Sarossa from Planescape: Torment---the twins)
This will clue them in to Dexter's involvement.
Ultimately; I envision the adventure climaxing with a massive ritual that the PCs may either interrupt, allow to be completed, or direct the flow. Dexter will attempt to subvert the ritual to HIS Ascension however.
But if all goes right, it will actually turn Aola the Proxy into the "New" Aoskar rather than restoring the Old Aoskar.
Honestly, I'm worried this is too close to Harbinger House and am interested in other options or takes.